In the Okavango Delta, 250,000 zebras set out on a yearly quest of over 174 miles. Though these zebras have been traveling this route for eons, they have recently had to tackle an impassable barrier.

In mating season the golden lion tamarin has no other choice but to cross the Trans-Amazonian Highway, a busy road where many semi-trucks pass. This obstacle could cause the loss of the tribe.

A railroad poses a new threat for Tibetan antelopes. Faced with this obstacle, the animals must resort to passing through mountain prairies, making it easy for their predators to attack.